South Korea says it has fired warning shots at North Korean fishing boats that crossed the disputed border between the two countries.

Seoul's defense ministry tells VOA that the South Korean navy fired the shots in response to the North Korean vessels, which were operating south of the volatile Yellow Sea maritime boundary off the countries' western coast.

Officials say the boats retreated after the warnings shots were fired. They say that several North Korean boats have crossed the disputed border over the past week, raising alert levels in South Korea's military.

The two Koreas have been technically in a state of war for more than 60 years. The agreement that ended the 1950-53 civil war was only a truce.